For example, in a conventional locking structure for a battery cover in a portable electronic device such as a portable phone, the battery cover is less prone to be removed with a battery accommodated in a device casing even if receiving an impact due to falling or the like and, on the other hand, the battery cover can be easily removed at the time of battery replacement (for example, refer to Patent Document 1).
In this conventional locking structure for a battery cover, when the battery cover is slid along a front surface of the device casing to be mounted on the device casing, an elastically-deformable engaging piece provided at a tip part of the battery cover is elastically deformed and is then elastically returned to be engaged with an engaging part provided inside the device casing. With this, the battery cover is made less prone to be removed even if receiving an impact due to falling or the like.
On the other hand, at the time of battery replacement, a plate-shaped elastic body provided at a portion on the front surface of the device casing corresponding to the engaging piece of the battery cover mounted on the device casing is pressed, thereby pressing down the engaging piece of the battery cover via this pressed plate-shaped elastic body to release the engagement of the engaging piece of the battery cover with the engaging part of the device casing. In this state, the battery cover is slid along the front surface of the device casing in a removing direction, thereby making the battery cover easily removable.    Patent Document 1: Japanese Laid-Open (Kokai) Publication No. Heisei 10-069895